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punctuated equilibriumdurchbrochenes Gleichgewicht (ger.)

Evolution that is characterized by long periods of stability in the characteristics of an organism and short periods of rapid change during which new forms appear especially from small subpopulations of the ancestral form in restricted parts of its geographic range; also: a theory or model of evolution emphasizing this. (Merriam Webster 2011)

The history of time is more adequately represented by a picture of »punctuated equilibria« than by the notion of phyletic gradualism. The history of evolution is not one of stately unfoldings, but a story of homeostatic equilibria, disturbed only »rarely« (i.e., rather often in the fullness of time) by rapid and episodic events of speciation.